Mineral-surfaced roofing material.



PATENT FREDERICK C. OVERBURY, OF HILLSDALE, NEW JERSEY, ASSIGNOR, BYMESNE AS- SIGNMENTS, TO THE FLINTKOTE COMPANY, OF BOSTON, MASSACHUSETTS,A COB- ]?OBATION OF MASSACHUSETTS.

MINERAL-SURFACEI) ROOFING MATERIAL.

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To all whom it may concern.-

Be it known that I, FREDERICK C. OVER- BURY, a citizen of the UnitedStates, residing at Hillsdale, in the county of Bergen and State of NewJersey, have invented new and useful Improvements in Mineral-surfacedRoofing Material, of which the following is a specification.

This invention relates to roofing fabrics of the type in which theexposed facing or coating consists of a relatively thick layer ofcrushed slate or analogous mineral material partially embedded in alayer of pitch, asphalt, or equivalent waterproof compound. In suchfabrics, the foundation consists of a sheet of felt or other fibrousmaterial saturated or impregnated with a bituminous or hydrocarboncompound, and on this compound so treated is applied a layer of pitch orasphalt or the like, in which the crushed mineral is embedded while saidlayer is in a plastic adhesive condition. Such roofings, in the form ofsheets, strips or shingles, are in great demand because of their roughappearance and due to the color effects pro duced by the mineralfacings.

In manufacturing and marketing such goods, I have found that itfrequently happens that the appearance of the fabric is injured due tothe fact that certain oily or greasy components of the saturating orcoat ing compounds reach the mineral material andv discolor it in spotsor patches. Further, when different batches of the fabric or roofing areheld in stock, even though formed of theraw material, they differ intint or shade, and, when laid on the same roof, produce unsatisfactoryresults.

In an earlier application, Serial No.

56,289, filed October 16, 1.915, I pointed out a method of curing thetrouble. As a result of further investigations and experimentation, Ihave discovered that, in lieu of spraying or otherwise treating themineral surface with the specific materials referred to in saidapplication for preventing the oily components of the bituminous orhydrocarbon saturating or coating components from discoloring the roughmineral Specification of Letters Patent.

Patented Sept. 42,1917.

Application filed January 20, 1917. Serial No. 143,502.

surface, I am able to secure still better results by employing dextrinas the main component of the surface-treating material. I preferably mixdextrin with hot water in the proportion of 1.6 pounds of dextrin toenough water to produce one gallon of the mixture, although theseproportions may be changed as desired. In case there should be anytendency for the dextrin to grow sour or to spoil, any suitablepreservative, such as bichlorid of mercury, may be used. If used, I donot employ the described preservaative in large amounts, as one partthereof to two thousand parts of the dextrin solution is sufficient.

As soon as the mineral-surfaced roofing fabric is produced, I treat itwith the dextrin solution, either by spray, or with a brush, or bydipping the surface in the solution, or applying the solution thereto bya roll. The solution spreads over the sheet in a thin film which doesnot mask the rough mineral surface, or act as a binder, but prevents theoily components from creeping over the slate or mineral particles anddiscoloring them. The film of the dextrin, when the water hasevaporated, is transparent, and it also acts to prevent the sticking ofone sheet of the fabric to the other when the sheets are superimposed.Of course any equivalent for dextrin may be used in its stead withoutdeparting from the scope of this invention.

Having thus explained the nature of my invention and one way ofproducing the de sired results, withoutsetting forth all of theembodiments of the invention and the different ways in which it may bepractised, what I claim is:

1. A weatherproof roofing fabric, having a bituminous coating and alayer of crushed mineral partially embedded therein, and having a filmof deXtrin on said crushed mineral. 2. The hereindescribed process whichconsists in treating the crushed-mineral face of a mineral-surfacedroofing fabric. with a liquid containing dextrin, to leave a film ofdextrin thereon.

3. The hereindesoribed process which con- :1 mineratsurfaced roofingfabric with an sists in treating the crushed-mineral face of aqueoussolution of dextrin, and a preservea mineral-sm'fuced roofing fabricwith an tive for the dextrin to leave a film of dextrin lJ aqueoussolution of dextrin to leave a film thereon. 5 of dext-rin thereon. Intestimony whereof I have affixed my 4. The hereindescribed process Whichconsignature. sists in treating the crushed-mineral face of FREDERICK C.OVERBURY.

